Compositions and methods for treating heart failure

ABSTRACT

The present invention provides methods for treating chronic heart failure patients using the medication comprising neuregulin. The methods comprise first performing a companion diagnostic test of each patient before treatment; and then providing a suitable treatment to the patient according to the results of the companion diagnostic test. When the result of the test is within a favorite treatment zone, the patient is suitable for heart failure treatment by administering an effective amount of neuregulin.

This application is a divisional application of U.S. patent applicationSer. No. 14/350,050, filed Apr. 4, 2014, which is a U.S. national stageapplication of PCT/CN2012/001354, having an international filing date ofOct. 8, 2012, which claims priority to PCT/CN2011/001691, having aninternational filing date of Oct. 10, 2011, and to PCT/CN2011/081699,having an international filing date of Nov. 2, 2011, each of which isincorporated herein by reference in its entirety and for all purposes.

The instant application contains a Sequence Listing which has beensubmitted electronically in ASCII format and is hereby incorporated byreference in its entirety. Said ASCII copy, created on Jun. 23, 2014, isnamed 11748-045-999_SL.txt and is 1,221 bytes in size.

FIELD OF THE INVENTION

The present invention relates to the use of neuregulin protein for thepreparation of medication for preventing, treating or delaying heartfailure in humans and methods for preventing, treating or delaying heartfailure in humans using said medication. Particularly, the presentinvention provides methods for preventing, treating or delaying heartfailure using the medication comprising a neuregulin protein in specificpopulations of chronic heart failure patients.

BACKGROUND OF THE INVENTION

Heart failure affects approximately five million Americans, and morethan 550,000 new patients are diagnosed with the condition each year.Current drug therapy for heart failure is primarily directed toangiotensin-converting enzyme (ACE) inhibitors, which are vasodilatorsthat cause blood vessels to expand, lowering blood pressure and reducingthe heart's workload. While the percent reduction in mortality has beensignificant, the actual reduction in mortality with ACE inhibitors hasaveraged only 3%-4%, and there are several potential side effects.Additional limitations are associated with other options for preventingor treating heart failure. For example, heart transplantation is clearlymore expensive and invasive than drug treatment, and it is furtherlimited by the availability of donor hearts. Uses of mechanical devices,such as biventricular pacemakers, are similarly invasive and expensive.Thus, there has been a need for new therapies given the deficiencies incurrent therapies.

One promising new therapy involves administration of neuregulin(hereinafter referred to as “NRG”) to a patient suffering from or atrisk of developing heart failure. NRGs, a family of EGF-like growthfactors, comprises a family of structurally related growth anddifferentiation factors that include NRG1, NRG2, NRG3 and NRG4 andisoforms thereof, are involved in an array of biological responses:stimulation of breast cancer cell differentiation and secretion of milkproteins; induction of neural crest cell differentiation to Schwanncells; stimulation of skeletal muscle cell synthesis of acetylcholinereceptors; and, promotion of myocardial cell survival and DNA synthesis.In vivo studies of neuregulin gene-targeted homozygous mouse embryoswith severe defects in ventricular trabecular formation and dorsal rootganglia development indicate that neuregulin is essential for heart andneural development.

NRGs bind to the EGF receptor family, which comprises EGFR, ErbB2, ErbB3and ErbB4, each of which plays an important role in multiple cellularfunctions, including cell growth, differentiation and survival. They areprotein tyrosine kinase receptors, consisting of an extracellularligand-binding domain, transmembrane kinase domain and cytoplasmictyrosine kinase domain. After NRG bind to the extracellular domain ofErbB3 or ErbB4, it induces a conformational change that leads toheterodimer formation between ErbB3, ErbB4 and ErbB2 or homodimerformation between ErbB4 itself, which results in phosphorylation of thereceptor's C-terminal domain inside the cell membrane. Thephosphorylated intracellular domain then binds additional signalproteins inside the cell, activating the corresponding downstream AKT orERK signaling pathway, and inducing a series of cell reactions, such asstimulation or depression of cell proliferation, cell differentiation,cell apoptosis, cell migration or cell adhesion. Among these receptors,mainly ErbB2 and ErbB4 are expressed in the heart.

It has been shown that the EGF-like domains of NRG-1, ranging in sizefrom 50 to 64-amino acids, are sufficient to bind to and activate thesereceptors. Previous studies have shown that neuregulin-1β (NRG-1β) canbind directly to ErbB3 and ErbB4 with high affinity. The orphanreceptor, ErbB2, can form heterdimer with ErbB3 and ErbB4 with higheraffinity than ErbB3 or ErbB4 homodimers. Research in neural developmenthas indicated that the formation of the sympathetic nervous systemrequires an intact NRG-1β, ErbB2 and ErbB3 signaling system. Targeteddisruption of the NRG-1β or ErbB2 or ErbB4 led to embryonic lethalitydue to cardiac development defects. Recent studies also highlighted theroles of NRG-1β, ErbB2 and ErbB4 in the cardiovascular development aswell as in the maintenance of adult normal heart function. NRG-1β hasbeen shown to enhance sarcomere organization in adult cardiomyocytes.The administration of a recombinant NRG-1β EGF-like domain significantlyimproves or protects against deterioration in myocardial performance indistinct animal models of heart failure as well as in clinical trials.These results make NRG-1 promising as a lead compound for the treatmentof heart failure. However, there is still a need for more evidences ofwhether NRG-1 treatment can provide long-term benefits to the heartfailure patients and whether the benefits can be provided to all chronicheart failure patients or some subpopulations.

SUMMARY OF THE INVENTION

In human clinical trials of neuregulin for treating heart failure,applicant discovered that evaluating New York Heart Association (NYHA)heart function classification or measuring plasma level of NT-proBNP orBNP in patients allows the selection of heart failure patients who willreceive significant treatment benefits from neuregulin. Such benefitsinclude significant reduction in mortality rate.

It has been discovered by applicant that NRG enhances cardiac musclecell differentiation and organization of sarcomeric and cytoskeletonstructure, as well as cell adhesion. It has been also discovered byapplicant that that NRG significantly improves or protects againstdeterioration in myocardial performance in distinct animal models ofheart failure and in clinical trials. Neuregulin, neuregulinpolypeptide, neuregulin derivatives, or compounds which mimic theactivities of neuregulins, fall within the scope of the presentinvention.

Thus, in a first aspect of the invention, a pharmaceutical compositioncomprise an effective amount of neuregulin is provided for treatingchronic heart failure patients, and the patients received significantbenefits from the pharmaceutical composition. In some embodiments, thebenefit is significant reduction of mortality rate. In some embodiments,the benefit is significant reduction of rehospitalization. In someembodiments, the benefit is the improvement of the biomarkers levelswhich indicate the improvement of chronic heart failure. In someembodiments, the pharmaceutical composition is administered to thepatients for an introduction regimen. In some optimized embodiments, theintroduction regimen includes an administration of the pharmaceuticalcomposition for at least consecutive 3, 5, 7 or 10 days. In someoptimized embodiments, the pharmaceutical composition is administered tothe patients for a maintenance regimen for at least 3, 6 or 12 monthsafter the introduction regimen. In some optimized embodiments, themaintenance regimen includes administration of the pharmaceuticalcomposition every 3, 5, 7 or 10 days.

In a second aspect, the invention provides a method to improve survivalor reduce mortality of chronic heart failure patients, comprisingadministering a pharmaceutical composition comprising an effectiveamount of neuregulin to the chronic heart failure patients. In someembodiments, the pharmaceutical composition is administered to thepatients for an introduction regimen. In some optimized embodiments, theintroduction regimen includes administration of the pharmaceuticalcomposition for at least consecutive 3, 5, 7 or 10 days. In someoptimized embodiments, the pharmaceutical composition is administered tothe patients for a maintenance regimen for at least 3, 6 or 12 monthsafter the introduction regimen. In some optimized embodiments, themaintenance regimen includes an administration of the pharmaceuticalcomposition every 3, 5, 7 or 10 days.

In a third aspect of the invention, a pharmaceutically effective amountof neuregulin is used for treating chronic heart failure patients whoseplasma level of NT-proBNP is within a favorite treatment zone prior toneuregulin treatment. In one embodiment, the favorite treatment zone isno more than 4000 fmol/ml. In another embodiment, the favorite treatmentzone is between 1600 fmol/ml and 4000 fmol/ml. In yet anotherembodiment, the favorite treatment zone is no more than 1600 fmol/ml. Inanother preferred embodiment, the plasma level is measured byimmunoassay.

In a fourth aspect of the invention, a pharmaceutically effective amountof neuregulin is used for treating chronic heart failure patients whohas a specific class of heart function classified by NYHA heart functionclassification. In some embodiments, the specific class of heartfunction is NYHA class II. In some embodiments, the specific class ofheart function is NYHA class III.

In a fifth aspect, the invention features a method of selecting a heartfailure patient for treatment by neuregulin. This method comprisesmeasuring the plasma level of NT-proBNP in the patient. In oneembodiment, a level of no more than 4000 fmol/ml is indicative of thepatient being suitable for heart failure treatment by neuregulin. Inanother embodiment, a level of between 1600 fmol/ml and 4000 fmol/ml isindicative of the patient being suitable for heart failure treatment byneuregulin. In yet another embodiment, a level of no more than 1600fmol/ml is indicative of the patient being suitable for heart failuretreatment by neuregulin.

In a sixth aspect, the invention features a method of selecting a heartfailure patient for treatment by neuregulin. This method comprisesevaluating heart function class by NYHA heart function classification.In one embodiment, NYHA class II is indicative of the patient beingsuitable for heart failure treatment by neuregulin. In anotherembodiment, NYHA class III is indicative of the patient being suitablefor heart failure treatment by neuregulin.

In a seventh aspect, the invention features a diagnostic kits forselecting a heart failure patient for treatment by neuregulin. In oneembodiment, the diagnostic kits comprises immunoassay reagents tomeasure plasma level of NT-proBNP in a heart failure patient wherein alevel of no more than 4000 fmol/ml is indicative of the patient beingsuitable for heart failure treatment by neuregulin. In anotherembodiment, a level of between 1600 fmol/ml and 4000 fmol/ml isindicative of the patient being suitable for heart failure treatment byneuregulin. In yet another embodiment, a level of no more than 1600fmol/ml is indicative of the patient being suitable for heart failuretreatment by neuregulin.

In a eighth aspect of the invention, the use of neuregulin protein forpreparation of a medication was provided. The medication can be providedto chronic heart failure patients for long-term benefits. In oneembodiment, the long-term benefit is the improvement of survival. In oneembodiment, the long-term benefit is the reduction ofre-hospitalization. In another embodiment, the long-term benefit is theimprovement of biomarkers which indicate the long-term prognosis ofchronic heart failure. In some embodiments, the medication isadministered to the patients for an introduction regimen. In someoptimized embodiments, the introduction regimen includes administrationof medication for at least consecutive 3, 5, 7 or 10 days. In someoptimized embodiments, the medication is administered to the patientsfor a maintenance regimen for at least 3, 6 or 12 months after theintroduction regimen. In some optimized embodiments, the maintenanceregimen includes an administration of the medication every 3, 5, 7 or 10days.

In a ninth aspect of the invention, a companion diagnostic test wasprovided for the treatment of chronic heart failure by neuregulinprotein. N-terminal pro-brain natriuretic peptide (NT-proBNP) is used asa biomarker for the companion diagnostic test. In one embodiment, alevel of no more than 4000 fmol/ml is indicative of the patient beingsuitable for heart failure treatment by neuregulin. In anotherembodiment, a level of between 1600 fmol/ml and 4000 fmol/ml isindicative of the patient being suitable for heart failure treatment byneuregulin. In yet another embodiment, a level of no more than 1600fmol/ml is indicative of the patient being suitable for heart failuretreatment by neuregulin.

In a tenth aspect of the invention, a method of treating chronic heartfailure using neuregulin is provided. The method comprises an evaluationprocedure before treatment and decides whether each patient is suitableto receive neuregulin treatment according to the result of theevaluation. In one embodiment, the evaluation procedure includes NYHAheart function classification of a chronic heart failure patient. Inanother embodiment, the evaluation procedure includes test of plasmaNT-proBNP or BNP for each chronic heart failure patient.

In a eleventh aspect of the invention, a companion diagnostic kit fordeciding whether a chronic heart failure patient is suitable forreceiving neuregulin protein treatment is provided. The companiondiagnostic kit comprises a test kit for plasma NT-proBNP or BNP and aninstruction of how to use the kit and how to judge whether the subjectis suitable for neuregulin protein treatment according to the testresult.

DETAILED DESCRIPTION OF THE INVENTION

For clarity of disclosure, and not by way of limitation, the detaileddescription of the invention hereinafter is divided into the subsectionsthat follow. All publications mentioned herein are incorporated byreference to disclose and describe the methods and/or materials inconnection with which the publications are cited.

A. Definitions

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as is commonly understood by one of ordinary skillin the art to which this invention belongs. All patents, applications,published applications and other publications referred to herein areincorporated by reference in their entirety. If a definition set forthin this section is contrary to or otherwise inconsistent with adefinition set forth in the patents, applications, publishedapplications and other publications that are herein incorporated byreference, the definition set forth in this section prevails over thedefinition that is incorporated herein by reference.

As used herein, the singular forms “a”, “an”, and “the” mean “at leastone” or “one or more” unless the context clearly dictates otherwise.

As used herein, “neuregulin” or “NRG” used in the present inventionrefers to proteins or peptides that can bind and activate ErbB2, ErbB3,ErbB4 or combinations thereof, including but not limited to allneuregulin isoforms, neuregulin EGF-like domain alone, polypeptidescomprising neuregulin EGF-like domain, neuregulin mutants orderivatives, and any kind of neuregulin-like gene products that alsoactivate the above receptors as described in detail below. Neuregulinalso includes NRG-1, NRG-2, NRG-3 and NRG-4 proteins, peptides,fragments and compounds that mimic the activities of neuregulin.Neuregulin used in the present invention can activate the above ErbBreceptors and modulate their biological reactions, e.g., stimulateacetylcholine receptor synthesis in skeletal muscle cell; and/or improvecardiocyte differentiation, survival and DNA synthesis. Neuregulin alsoincludes those variants with conservative amino acid substitutions thatdo not substantially alter their biological activity. Suitableconservative substitutions of amino acids are known to those of skill inthis art and may be made generally without altering the biologicalactivity of the resulting molecule. Those of skill in this art recognizethat, in general, single amino acid substitutions in non-essentialregions of a polypeptide do not substantially alter biological activity(see, e.g., Watson et al., Molecular Biology of the Gene, 4^(th)Edition, 1987, The Bejacmin/Cummings Pub.co., p. 224). In preferredembodiments, neuregulin used in the present invention binds to andactivates ErbB2/ErbB4 or ErbB2/ErbB3 heterodimers, for example, but notfor the purpose of restriction, peptides including the 177-237 residuesof NRG-1 β2 isoform containing the amino acid sequence:SHLVKCAEKEKTFCVNGGECF MVKDLSNPSRYLCKCPNEFTGDRCQNYVMASFYKAEELYQ (SEQ IDNO:1). The peptides including the 177-237 residues of NRG-1 (β2 isoformcomprises the EGF-like domain, which has been proved to be sufficient tobind to and activate the receptors.

As used herein, “epidermal growth factor-like domain” or “EGF-likedomain” refers to a polypeptide motif encoded by the neuregulin genethat binds to and activates ErbB2, ErbB3, ErbB4, or combinationsthereof, and bears a structural similarity to the EGF receptor-bindingdomain as disclosed in WO 00/64400, Holmes et al., Science,256:1205-1210 (1992); U.S. Pat. Nos. 5,530,109 and 5,716,930; Hijazi etal., Int. J. Oncol., 13:1061-1067 (1998); Chang et al., Nature,387:509-512 (1997); Carraway et al., Nature, 387:512-516 (1997);Higashiyama et al., J. Biochem., 122:675-680 (1997); and WO 97/09425,the contents of which are all incorporated herein by reference. Incertain embodiments, EGF-like domain binds to and activates ErbB2/ErbB4or ErbB2/ErbB3 heterodimers. In certain embodiments, EGF-like domaincomprises the amino acid sequence of the receptor binding domain ofNRG-1. In some embodiments, EGF-like domain comprises the amino acidsequence corresponding to amino acid residues 177-226, 177-237, or177-240 of NRG-1. In certain embodiments, EGF-like domain comprises theamino acid sequence of the receptor binding domain of NRG-2. In certainembodiments, EGF-like domain comprises the amino acid sequence of thereceptor binding domain of NRG-3. In certain embodiments, EGF-likedomain comprises the amino acid sequence of the receptor binding domainof NRG-4. In certain embodiments, EGF-like domain comprises the aminoacid sequence of Ala Glu Lys Glu Lys Thr Phe Cys Val Asn Gly Gly Glu CysPhe Met Val Lys Asp Leu Ser Asn Pro (SEQ ID NO: 2), as described in U.S.Pat. No. 5,834,229.

The formulation, dosage and route of administration of a neuregulinprotein, preferably in the form of pharmaceutical compositions, can bedetermined according to the methods known in the art (see e.g.,Remington: The Science and Practice of Pharmacy, Alfonso R. Gennaro(Editor) Mack Publishing Company, April 1997; Therapeutic Peptides andProteins: Formulation, Processing, and Delivery Systems, Banga, 1999;and Pharmaceutical Formulation Development of Peptides and Proteins,Hovgaard and Frkjr (Ed.), Taylor & Francis, Inc., 2000; MedicalApplications of Liposomes, Lasic and Papahadjopoulos (Ed.), ElsevierScience, 1998; Textbook of Gene Therapy, Jain, Hogrefe & HuberPublishers, 1998; Adenoviruses: Basic Biology to Gene Therapy, Vol. 15,Seth, Landes Bioscience, 1999; Biopharmaceutical Drug Design andDevelopment, Wu-Pong and Rojanasakul (Ed.), Humana Press, 1999;Therapeutic Angiogenesis: From Basic Science to the Clinic, Vol. 28,Dole et al. (Ed.), Springer-Verlag New York, 1999).

The neuregulin protein, can be formulated for oral, rectal, topical,inhalational, buccal (e.g., sublingual), parenteral (e.g., subcutaneous,intramuscular, intradermal, or intravenous), transdermal administrationor any other suitable route of administration. The most suitable routein any given case will depend on the nature and severity of thecondition being treated and on the nature of the particular neuregulinprotein, which is being used. The neuregulin protein can be administeredalone. Alternatively and preferably, the neuregulin protein isco-administered with a pharmaceutically acceptable carrier or excipient.Any suitable pharmaceutically acceptable carrier or excipient can beused in the present method (See e.g., Remington: The Science andPractice of Pharmacy, Alfonso R. Gennaro (Editor) Mack PublishingCompany, April 1997).

According to the present invention, the neuregulin protein, alone or incombination with other agents, carriers or excipients, may be formulatedfor any suitable administration route, such as intracavernous injection,subcutaneous injection, intravenous injection, intramuscular injection,intradermal injection, oral or topical administration. The method mayemploy formulations for injectable administration in unit dosage form,in ampoules or in multidose containers, with an added preservative. Theformulations may take such forms as suspensions, solutions or emulsionsin oily or aqueous vehicles, and may contain formulatory agents such assuspending, stabilizing and/or dispersing agents. Alternatively, theactive ingredient may be in powder form for constitution with a suitablevehicle, sterile pyrogen-free water or other solvents, before use.Topical administration in the present invention may employ the use of afoam, gel, cream, ointment, transdermal patch, or paste.

Pharmaceutically acceptable compositions and methods for theiradministration that may be employed for use in this invention include,but are not limited to those described in U.S. Pat. Nos. 5,736,154;6,197,801 B1; 5,741,511; 5,886,039; 5,941,868; 6,258,374 B1; and5,686,102.

The magnitude of a therapeutic dose in the treatment or prevention willvary with the severity of the condition to be treated and the route ofadministration. The dose, and perhaps dose frequency, will also varyaccording to age, body weight, condition and response of the individualpatient.

It should be noted that the attending physician would know how to andwhen to terminate, interrupt or adjust therapy to lower dosage due totoxicity, or adverse effects. Conversely, the physician would also knowhow to and when to adjust treatment to higher levels if the clinicalresponse is not adequate (precluding toxic side effects).

Any suitable route of administration may be used. Dosage forms includetablets, troches, cachet, dispersions, suspensions, solutions, capsules,patches, and the like. See, Remington's Pharmaceutical Sciences. Inpractical use, the neuregulin protein, alone or in combination withother agents, may be combined as the active in intimate admixture with apharmaceutical carrier or excipient, such as beta-cyclodextrin and2-hydroxy-propyl-beta-cyclodextrin, according to conventionalpharmaceutical compounding techniques. The carrier may take a wide formof preparation desired for administration, topical or parenteral. Inpreparing compositions for parenteral dosage form, such as intravenousinjection or infusion, similar pharmaceutical media may be employed,water, glycols, oils, buffers, sugar, preservatives, liposomes, and thelike known to those of skill in the art. Examples of such parenteralcompositions include, but are not limited to dextrose 5% w/v, normalsaline or other solutions. The total dose of the neuregulin protein,alone or in combination with other agents to be administered may beadministered in a vial of intravenous fluid, ranging from about 1 ml to2000 ml. The volume of dilution fluid will vary according to the totaldose administered.

The invention also provides for kits for carrying out the therapeuticregimens of the invention. Such kits comprise in one or more containerstherapeutically effective amounts of the neuregulin protein, alone or incombination with other agents, in pharmaceutically acceptable form.Preferred pharmaceutical forms would be in combination with sterilesaline, dextrose solution, or buffered solution, or otherpharmaceutically acceptable sterile fluid. Alternatively, thecomposition may be lyophilized or desiccated; in this instance, the kitoptionally further comprises in a container a pharmaceuticallyacceptable solution, preferably sterile, to reconstitute the complex toform a solution for injection purposes. Exemplary pharmaceuticallyacceptable solutions are saline and dextrose solution.

In another embodiment, a kit of the invention further comprises a needleor syringe, preferably packaged in sterile form, for injecting thecomposition, and/or a packaged alcohol pad. Instructions are optionallyincluded for administration of composition by a physician or by thepatient.

As used herein, “treat”, “treatment” and “treating” refer to any mannerin which the symptoms of a condition, disorder or disease areameliorated or otherwise beneficially altered. The effect may beprophylactic in terms of completely or partially preventing a disease orsymptom thereof and/or may be therapeutic in terms of a partial orcomplete cure for a disease and/or adverse effect attributable to thedisease. Treatment also encompasses any pharmaceutical use of thecompositions herein.

As used herein, “heart failure” means an abnormality of cardiac functionwhere the heart does not pump blood at the rate needed for therequirements of metabolizing tissues. Heart failure includes a widerange of disease states such as congestive heart failure, myocardialinfarction, tachyarrhythmia, familial hypertrophic cardiomyopathy,ischemic heart disease, idiopathic dilated cardiomyopathy, myocarditisand the like. The heart failure can be caused by any number of factors,including, without limitation, ischemic, congenital, rheumatic, viral,toxic or idiopathic forms. Chronic cardiac hypertrophy is asignificantly diseased state which is a precursor to congestive heartfailure and cardiac arrest.

As used herein, “protein” is synonymous with “polypeptide” or “peptide”unless the context clearly dictates otherwise.

As used herein, “plasma” is synonymous with “serum” unless the contextclearly dictates otherwise.

As used herein, “long-term benefit” means benefit caused by a treatmentor interference which may not be observed in a short period after thetreatment or interference. For chronic heart failure patients, long-termbenefit may be improvement of survival, reduction of re-hospitalizationor improvement of biomarkers which indicate the long-term prognosis. Insome embodiments, the time period for observation of the benefit isabout 6 months. In some embodiments, the time period for observation ofthe benefit is about 1 year. In some embodiments, the time period forobservation of the benefit is about 2 years. And in other embodiments,the time period for observation of the benefit is about 3 years, 5years, 10 years or longer.

As used herein, “survival” means the time or probability one subject mayremain alive or living. It could be expressed by survival time orsurvival rate. Survival time is the time period start from the diagnosisor treatment to the end of the life. Survival rate means the percentageof people who are alive for a given period of time after diagnosis ortreatment. For each subject, prolonged survival time caused by atreatment or interference could be regarded as a benefit. For a group ofsubjects or large populations, prolonged mean survival time or increasedsurvival rate could be regarded as a benefit.

As used herein, “re-hospitalization” means the times or frequency of thepatient admitted to the hospital in a given period of time. Theadmission to the hospital may be caused by all conditions, or onlycaused by the same condition which is being treated. For each subject, areduction of times of re-hospitalizations in a given period of timecould be regarded as a benefit. And for a group of subjects or largepopulations, a reduction of total times or mean times ofre-hospitalizations could be regarded as a benefit.

As used herein, “N-terminal brain natriuretic peptide” or “NT-proBNP”means the inactive remnant N-terminal proBNP, the latter is the prohormone of BNP which is a hormonally active natriuretic peptide that ismainly released from the cardiomyocytes in the left ventricular wall. Inreaction to stretch and tension of the myocardial wall the pro hormoneproBNP splits into BNP and the hormonally inactive remnant NT-proBNP byproteolytic cleavage.

BNP and NT-proBNP plasma levels are promising tools in the dailymanagement of suspected or established heart failure. Most studies onthe use of BNP and NT-proBNP in clinical practice addressed theirdiagnostic properties, and an increasingly amount of evidence isavailable supporting the prognostic value of BNP and NT-proBNP. AsNT-proBNP has about 6 times longer of half-life in the blood than BNP,it is more widely used as a diagnostic or prognostic marker for heartfailure. The plasma NT-proBNP level can be analyzed by commercial kits.For the purpose of example, but not limitation, the commercial kits fromRoche or Biomedica. In the examples of the present invention, theNT-proBNP level was detected by kit from Biomedica (Austria).

Both BNP and NT-proBNP levels in the blood are used for screening,diagnosis of heart failure and are useful to establish prognosis inheart failure, as both markers are typically higher in patients withworse outcome. And, it is discovered in the present invention thatplasma level of BNP or NT-proBNP is indicative of the patient beingsuitable for heart failure treatment by neuregulin. In fact, anydiagnostic or prognostic markers for heart failure can be used todetermine whether a patient is suitable for heart failure treatment byneuregulin. The plasma level of NT-proBNP identified in this inventionshall be used as guidance rather than a limitation for selection ofheart failure patients who will receive significant treatment benefitsfrom neuregulin. For example, using a plasma level of 5000 fmol/ml isstill able to select heart failure patients who will receive treatmentbenefits from neuregulin, but some of these patients will receivetreatment benefits in a lesser degree.

As used herein, “New York Heart Association” or “NYHA” heart functionclassification is a simple way of classifying the extent of heartfailure. It places patients in one of four categories based on how muchthey are limited during physical activity; the limitations/symptoms arein regards to normal breathing and varying degrees in shortness ofbreath and/or angina pain: I, no symptoms and no limitation in ordinaryphysical activity, e.g. shortness of breath when walking, climbingstairs etc.; II, mild symptoms (mild shortness of breath and/or angina)and slight limitation during ordinary activity; III, marked limitationin activity due to symptoms, even during less-than-ordinary activity,e.g. walking short distances (20-100 m), comfortable only at rest; andIV, severe limitations, experiences symptoms even while at rest, mostlybedbound patients.

As used herein, “activity unit” or “EU” or “U” means the quantity ofstandard product that can induce 50% maximal reaction. In other words,to determine the activity unit for a given active agent, the EC50 mustbe measured. For example, if the EC50 for a batch of product was 0.1 μg,which would be one unit. Further, if 1 μg of that product is being used,then 10 EU (1/0.1) is being used. The EC50 can be determined by anymethod known in the art, including the method employed by the inventors.This determination of the activity unit is important for quality controlof genetically engineered products and clinically used drugs, permitsproduct from different pharmaceuticals and/or different batch numbers tobe quantified with uniform criteria.

The following is an exemplary, rapid, sensitive, high flux andquantitative method for determination of biological activity of NRG-1through combining NRG with cell surface ErbB3/ErbB4 molecule andindirect mediation of ErbB2 phosphorylation (See e.g., Michael D. Sadicket al., 1996, Analytical Biochemistry, 235:207-214 and WO03/099300).

Briefly, the assay, termed a kinase receptor activation enzyme-linkedimmunosorbant assay (KIRA-ELISA), consists of two separate microtiterplates, one for cell culture, ligand stimulation, and celllysis/receptor solubilization and the other plate for receptor captureand phosphotyrosine ELISA. The assay was developed for analysis ofNRG-induced ErbB2 activation and utilizes the stimulation of intactreceptor on the adherent breast carcinoma cell line, MCF-7. Membraneproteins are solubilized via Triton X-100 lysis and the receptor iscaptured in ELISA wells coated with ErbB2-specific antibodies with nocross-reaction to ErbB3 or ErbB4. The degree of receptor phosphorylationis then quantified by antiphosphotyrosine ELISA. A reproducible standardcurve is generated with a EC50 of approximately 360 pM for heregulinbeta 1 (177-244). When identical samples of HRG beta 1 (177-244) areanalyzed by both the KIRA-ELISA and quantitative antiphosphotyrosineWestern Blot analysis, the results correlate very closely with oneanother. The assay described in this report is able to specificallyquantify tyrosine phosphorylation of ErbB2 that results from theinteraction of HRG with ErbB3 and/or ErbB4.

Since most of the genetically engineered medicines are proteins andpolypeptides, their activity can be determined by their amino acidsequences or the activity center formed by their spatial structure.Activity titer of protein and polypeptide is not consistent with theirabsolute quality, therefore cannot be determined with weight unit asthat of chemical drugs. However, biological activity of geneticallyengineered medicines is generally consistent with their pharmacodynamicsand titer determination system established through given biologicalactivity can determine its titer unit. Therefore, biological activitydetermination can be part of a titration process of the substance withbiological activity and is an important component of quality control ofgenetically engineered product. It is important to determine biologicalactivity criteria for quality control of genetically engineered productand clinically used drugs.

Quantity of standard product that can induce 50% maximal reaction isdefined as an activity unit (1 EU). Accordingly, product from differentpharmaceuticals and of different batch numbers can be quantitated withuniform criteria.

B. Examples Example 1 The Effect of Neucardin™ Administration byDifferent Routes on the Survival Rate of Rats with CHF

Introduction:

In this study, we used a coronary artery ligation (CAL) induced CHFmodel to investigate whether administration of Neucardin™ by IV dripusing a micro-injection pump or by subcutaneous (SC) bolus had anyeffects on survival rate and cardiac hemodynamics, 120 days after theinitiation of administration of Neucardin™ 4 weeks after CAL.Echocardiography and cardiac remodeling were also used to determinecardiac function and recovery from CAL.

2. Methods:

2.1. Test Animals:

Strain, Origin: Wistar rats, Shanghai SLAC Laboratory Animal CO.

LTD; Weight, 200±10 g, male;

2.2 Test Article:

2.2.1 Neucardin™

Identification: Recombinant human neuregulin-1 for injection (rhNRG-1,Neucardin™)

Lot Number: 200607009

Manufacturer: Zensun (Shanghai) Sci & Tech Co., Ltd

Dose form: Lyophilized powder

Appearance: White or off-white cake

Labeled Content of rhNRG-1: 250 μg/vial

Specific activity: 4897 U/vial

Storage conditions: 2-8° C.

2.2.2 Vehicle:

Identification: Placebo for recombinant human neuregulin-1

Dose form: Lyophilized powder

Appearance: White or off-white cake

Composition: Human serum albumin, mannitol, phosphate, NaCl

Storage conditions: 2-8° C.

2.3 Procedure:

2.3.1 To Establish the Rat CHF Model:

The LAD of the rats was ligated. Briefly, the rats were anesthetizedwith ketamine hydrochloride (100 mg/kg, IP) and their chest was shavedand sterilized. The rats were endotracheally intubated and mechanicallyventilated with room air (respiratory rate 60 breaths/min, tidal volume20 ml). A left thoracotomy was then performed at the 4th and 5thintercostal space and then the skin was incised along the left sternalborder. The fourth rib was then cut proximal to the sternum. Thepericardial sac was perforated and the heart was exposed. The LAD wasligated approximately 2 mm from its origin using a 6-0 silk suture.Subsequently, the air within the thorax was removed and the chest wasclosed in three layers (ribs, muscles and then skin). The rats were thenallowed to resume spontaneous respiration, recover from the anesthesiaand were then returned to their cages. Rats were maintained during aperiod of 4 weeks, then echocardiography evaluated, included in theformal study if they were shown an EF % value of 30-45%. Animals fromall Groups were housed 5 per cage, fed ad libitum with standard diet andhad free access to pure water. Room temperature was maintained at 21±1°C. and in a 12 h light/dark cycle.

2.3.2 IV Drip Via Microinjection Pump:

The method of IV drip of vehicle or Neucardin™ was through the tailvein. For this procedure, an appropriate rat restrainer was usedaccording to the weight of the animal. The rat was placed near therestrainer and was gently placed into the apparatus. Normally the ratsentered the restrainer without aid. Subsequently the tail of the rat wasswabbed with a gauze dampened with alcohol to increase blood flow to thetail vein and to the intenerate skin corneum. The two lateral (on theside) tail veins were located and with the bevel of the needle facingupward with the needle almost parallel to the vein, the needle wasinserted 2 mm into the tail vein 2-3 cm from the end of the tail. Toconfirm that the needle was successfully inserted into the tail vein,blood was extracted into the hub of the needle. The needle was fixedinto the tail using medical tape. The infusion of drug or vehicle at theappropriate rate (0.2-0.4 ml/h) by microinjection pump or bolusinjection was initiated.

2.3.3 SC Bolus

The SC bolus of vehicle or Neucardin™ was from the back of the rat. Forthis procedure, an appropriate rat restrainer was used according to theweight of the animal. The back of the rat was swabbed with gauzedampened with alcohol to sterilize the skin. With the bevel of theneedle facing upward with the needle almost parallel to the skin, theneedle was subcutaneously inserted 3-4 cm into the back of the rat. Theneedle was fixed onto the back using medical tape and connected to theperfusion tube. Then, the rat was placed near the restrainer and wasgently placed into the apparatus. Normally the rats entered therestrainer with no aid. After fasten the restrainer, the bolus injectionwas initiated.

2.3.4 Experiment Groups and Drug Infusion:

MI rats were randomized by EF % value into four Groups as follows:

Group A (Negative control) for both IV and SC bolus. n=58 rats: IV dripof vehicle for 10-days by micro-injection pump at a speed of 0.2 ml/hfor 8 h each day for the first 10 days, SC bolus of vehicle (same volumeas Neucardin™), every 5 days until Day 120;

Group B (SC bolus Neucardin™), n=58: IV drip of vehicle bymicro-injection pump at a speed of 0.2 ml/h for 8 h each day in thefirst 10 days, SC bolus Neucardin™ (10 μg/day), every 5 days until Day120;

Group C (IV drip Neucardin™), n=57: IV drip of Neucardin™ (0.625μg/kg/h) by micro-injection pump at a speed of 0.2 ml/h for 8 h each dayfor the first 10 days, SC bolus of vehicle (same volume as Neucardin™),every 5 days until Day 120.

Group D (IV drip and SC bolus Neucardin™), n=57: IV drip of Neucardin™(0.625 μg/kg/h) by micro-injection pump at a rate of 0.2 ml/h for 8 hper day for the first 10 days, SC bolus of vehicle (same volume asNeucardin™) at 1st, 6th, 11th day, and then SC bolus Neucardin™ (10μg/kg), every 5 days from 16th day to the end.

2.3.5 Data Acquisition

Survival rate; Echocardiography parameters; Hemodynamics parameters;

3. Results

3.1 Survival Rate:

Table 1 illustrates the survival rates between each Group. The survivalrates were 48.3%, 62.1%, 64.9% and 82.5% in the IV drip & SC bolus ofvehicle Group A, SC bolus of Neucardin™ Group B, IV drip of Neucardin™Group C and IV drip & SC bolus of Neucardin™ Group D, respectively. Allthe survival rate or mean survival time of mortalities in Group B, C andD were improved or prolonged compared to Group A with Group D had bestefficacy.

TABLE 1 Mortality, Survival rate and Mean survival time in the fourGroups Survival Mean survival Start rat rat Survival time of mortalitiesGroup Treatment number Deaths number rate (%) in days ± S.E. A Vehicle58 30 28 48.3% 83.8 ± 5.9 B SC bolus Neucardin ™ 58 22 36 62.1% 91.4 ±5.5 C IV drip Neucardin ™ 57 20 37 64.9% 97.5 ± 5.1 D SC bolus & IV dripNeucardin ™ 57 10 47 82.5% 107.5 ± 4.1 

3.2 Echocardiography Parameters:

Echocardiography parameters were shown in Table 2. Four-weeks aftercoronary artery ligation and before administration of the test article,the CHF rats were randomized into four Groups according to their EF %values. As shown in Table 2, there were no significant differencesbetween the four Groups before treatment (BT). 120 days after the startof administration, the EF % values were 30.7±3.1, 32.9±4.1, 33.5±3.4,36.2±4.8% in the vehicle, Neucardin™ via SC bolus, Neucardin™ via IVdrip and Neucardin™ via IV drip plus SC bolus Groups, respectively.After treatment, EF % and FS % of Group B, C and D were all higher thanthat of Group A.

TABLE 2 Echocardiography parameters in the four Groups BT LVEDd LVEDs EF% FS % Group AT N (cm) (cm) (%) (%) A. Negative control BT 58 0.987 ±0.083 0.829 ± 0.088 38.0 ± 5.5 16.2± AT 25 1.100 ± 0.089 0.961 ± 0.09030.7 ± 3.1 12.7± B. SC bolus Neucardin ™ BT 58 0.992 ± 0.066 0.831 ±0.066 38.2 ± 4.0 16.3± AT 33 1.104 ± 0.063 0.952 ± 0.070 33.1 ± 4.113.9± C. IV drip Neucardin ™ BT 57 0.985 ± 0.061 0.824 ± 0.068 38.5 ±4.4 16.3± AT 36 1.080 ± 0.072 0.929 ± 0.073 33.4 ± 3.4 14.0± D. SC bolus& IV drip Neucardin ™ BT 57 0.979 ± 0.065 0.818 ± 0.066 38.7 ± 4.3 16.5±AT 44 1.052 ± 0.087 0.893 ± 0.092 36.2 ± 4.8 15.3± BT: Before treatment;AT: After treatment;

3.3 Hemodynamic Parameters:

Table 3 shows the MAP, HR, ±dp/dt, LVEDP and LVSP values as measured inthe four Groups of anesthetized animals on day 121. When Neucardin™ wasadministered by SC bolus or by IV drip alone (Group B and C), Neucardin™significantly increased dp/dt and −dp/dt by 19.6% and 27.1%, 22.5% and29.8% compared to Group A. When Neucardin™ was administered by both IVdrip and SC bolus routes (Group D), significant increases in meanarterial pressure (MAP, 112.3±5.5 mmHg), left ventricular systolicpressure (LVSP, 139.4±9.8 mmHg), +dp/dt (7012.1±903.0 mmHg/s), −dp/dt(−4353.2±847.6 mmHg/s) compared to vehicle were obtained. Interestingly,these values of MAP, LVSP, +dp/dt and dp/dt were 10.6%, 9.2%, 38.5% and37.8% higher than vehicle treated rats, respectively. The results showedthat Group B, C and D were all better than Group A in hemodynamicparameters with Group D had best efficacy.

TABLE 3 Hemodynamics parameters in the four Groups SBP DBP MAP LVSPGroup Treatment N (mmHg) (mmHg) (mmHg) (mmHg) A Vehicle 14 118.7 ± 11.5 94.1 ± 12.3  102.3 ± 11.7 128.5 ± 14.7 B SC bolus Neucardin ™ 27 123.8± 11.5 95.3 ± 8.9 104.9 ± 9.5 129.5 ± 13.6 C IV drip Neucardin ™ 25122.5 ± 10.5 95.0 ± 7.5 104.4 ± 8.2 131.7 ± 10.0 D SC bolus & IV dripNeucardin ™ 35 132.6 ± 7.1  102.1 ± 5.3  112.3 ± 5.5 139.4 ± 9.8  LVEDPdp/dt (−dp/dt) Heart rate Group Treatment N (mmHg) (mmHg/s) (mmHg/s)(Beat/min) A Vehicle 14 5.8 ± 3.5 4995.6 ± 532.2 3087.5 ± 715.7 297.2 ±16.0 B SC bolus Neucardin ™ 27 4.5 ± 2.8  6050.9 ± 1231.3 4013.8 ± 838.3292.6 ± 23.0 C IV drip Neucardin ™ 25 4.0 ± 3.2 6199.9 ± 709.5 4098.9 ±823.5 296.3 ± 13.5 D SC bolus & IV drip Neucardin ™ 35 3.9 ± 2.5 7012.1± 903.0 4353.2 ± 847.6 292.5 ± 19.1

4. Conclusion

A combined administration of Neucardin™ by IV drip & SC bolus oradministration of the peptide given by each route alone all increasedthe survival rate of rats with CHF induced by CAL and improved cardiacfunctional parameters compared to rats treated with vehicle.

Example 2 A Randomized, Double-Blinded, Multi-Center, Placebo ControlledStudy to Evaluate the Efficacy and Safety of Recombinant HumanNeuregulin 1 in Patients with Chronic Heart Failure Based on StandardTreatment

To evaluate the efficacy of recombinant human neuregulin-1 for injectionon chronic heart failure, a phase II, double-blinded, multi-center,placebo controlled, standard treatment based study was carried out inmultiple clinical centers in China. A total of 195 patients with NYHAClass II or III stable chronic heart failure were enrolled andrandomized into three groups: placebo, or 0.6 μg/kg and 1.2 μg/kg ofrhNRG-1. There were no significant variations in demographics orbackground therapies among groups. According to the schedule, patientswere administered the drug for 10 consecutive days in the hospitalfirst, after finishing the day 11 follow up, they were discharged fromthe hospital. Another two on site follow up were at day 30 and day 90. Atelephone interview was conducted one year after the last patientenrolled.

Investigational Product:

Specification: Neucardin™, 61 amino acid polypeptide comprises theEGF-like domain of Neuregulin-1 β2 isoform, with the molecular weight of7054 Dal (1 μg=0.14 nmol). 250 μg (5000 EU)/vial (1 μg=20 EU).

Preparation: For injection.

Mode of administration: Intravenously drip.

Storage: in safe place, with limited access and protected from light, at3-8° C.

Placebo:

Specification: Excipient for Neucardin™ (250 μg/vial without activerecombinant human neuregulin-1 protein).

Dosage groups:

Dosage 0 μg/kg/day 0.6 μg/kg/day 1.2 μg/kg/day AdministrationIntravenous infusion Volume 50 ml Course 10 hours per day, forconsecutive 10 days

Study Procedure

Criteria for participation in the trial included patients with CHF (NYHAclass II or III) between the ages of 18 and 65 years old, LVEF≤40%, inrelatively stable clinical condition (including clinical signs, symptomsand accepted standard treatment for CHF at the target dose or maximumtolerance dose for over 1 month). Major exclusion criteria includedacute myocardial infarction, hypertrophic cardiomyopathy, constrictivepericarditis, significant valve disease or congenital heart disease,severe pulmonary hypertension, systolic blood pressure <90 mmHg or >160mmHg, severe ventricular arrhythmia, cardiac surgery or acerebrovascular event within the previous six months, claustrophobia orpregnant female subjects. All patients provided witnessed writtenconsent.

Patients were randomly assigned to three groups, treated with placebo orrhNRG-1 (0.6 or 1.2 μg/kg/day) for 10 consecutive days, after finishingthe day 11 follow up, they were discharged from the hospital. Anothertwo on site follow up were at day 30 and day 90. Blood samples of eachpatient were collected before treatment and at day 11, 30 and 90. PlasmaNT-proBNP was tested in the core lab with NT-proBNP assays (kit fromBiomedica). One year after the last patient enrolled, the telephoneinterview was made for collecting the information ofre-hospitalizations, all telephone interviews were recorded in a specialform with investigators signature.

Of the 48 patients with available re-hospitalization information in theplacebo group, 12 (25.0%) were rehospitalized for worsening heartfailure at least once. For the 0.6 μg/kg group, only 4 (8.7%) of the 46patients readmitted to the hospital (P=0.05 compared to placebo);Rehopitalization rate of the 1.2 μg/kg group was 22.0% (11/50). Theaverage times of re-hospitalizations was 0.458 (22/48) per patient inthe placebo group, while they were reduced by 57.4% and 17.0%respectively in the 0.6 (8/41) and 1.2 μg/kg group (19/50).

In the placebo group, the NT-proBNP were almost the same during thestudy while compare to the baseline. At day 11, the NT-proBNP wassignificantly increased in rhNRG-1 treated groups (from 1853±1512 to2399±1841 fmol/ml in 0.6 m/kg group, P<0.01; from 1562±1275 to 2774±1926fmol/ml in 1.2 μg/kg group, P<0.01). But his increase was transient andwas not caused by a worsening heart function as the cardiac functionshown to be increased, the NT-proBNP decreased to the baseline level atDay 30 and Day 90 in the 1.2 m/kg group. Moreover, in the 0.6 m/kggroup, the NT-proBNP was significantly reduced at day 30 (1323±1124fmol/ml, P=0.01) and day 90 (1518±1403 fmol/ml, P=0.01) while compare tothe baseline.

These results showed that rhNRG-1 treatment can reduce there-hospitalizations and the plasma level of NT-proBNP, which mayindicate rhNRG-1 can provide long-term benefits to chronic heart failurepatients.

Example 3 A Randomized, Double-Blinded, Multi-Center, Placebo ControlledSurvival Study of Recombinant Human Neuregulin 1 in Patients withChronic Heart Failure Based on Standard Treatment

To evaluate the efficacy of recombinant human neuregulin-1 for injectionon chronic heart failure, a phase II, double-blinded, multi-center,placebo controlled, standard treatment based study was carried out inmultiple clinical centers in China. A total of 351 patients with NYHAClass III or IV stable chronic heart failure were enrolled andrandomized into placebo group or rhNRG-1 group (0.6 m/kg). There were nosignificant variations in demographics or background therapies amonggroups. According to the schedule, patients were administered with thedrug for 10 consecutive days in the hospital, after finishing the day 11follow up, they were discharged from the hospital, and were administeredwith the drug once weekly from the 3^(rd) week till the 25^(th) week asout-patient. Blood samples of each patient were collected beforetreatment (baseline) and at each follow up. Plasma NT-proBNP level wastested in the core lab with NT-proBNP assays (kit from Biomedica). Thesurvival information was collected at 52th week of the study.

Investigational product:

Specification: Neucardin™, 61 amino acid polypeptide comprises theEGF-like domain of Neuregulin-1 β2 isoform, with the molecular weight of7054 Dal (1 μg=0.14 nmol). 250 μg (5000 EU)/vial (1 μg=20 EU).

Preparation: For injection.

Mode of administration: Intravenously drip or infusion.

Storage: in safe place, with limited access and protected from light, at3-8° C.

Placebo:

Specification: Excipient for Neucardin™. 250 m/vial and without activerecombinant human neuregulin-1 protein.

Dosage and regimens:

Day 1-10 Week 3-25 Dose 0.6 μg/kg/day rhNRG-1 0.8 μg/kg/day rhNRG-1 orplacebo or placebo Route Intravenous drip Intravenous infusion regimen10 hours per day for 10 days 10 minutes infusion weekly

Criteria for participation in the trial included patients with CHF (NYHAclass III or IV) between the ages of 18 and 80 years old, LVEF≤40%, inrelatively stable clinical condition (including clinical signs, symptomsand accepted standard treatment for CHF at the target dose or maximumtolerance dose for over 1 month). Major exclusion criteria includedacute myocardial infarction, hypertrophic cardiomyopathy, constrictivepericarditis, significant valve disease or congenital heart disease,severe pulmonary hypertension, systolic blood pressure<90 mmHg or >160mmHg, severe ventricular arrhythmia, cardiac surgery or acerebrovascular event within the previous six months, claustrophobia orpregnant female subjects. All patients provided witnessed writtenconsent.

The all-cause mortality of the placebo group at 52 week is 15.91%, with28 death in 176 patients, while the number is 9.71% in rhNRG-1 group,with 16 death in 175 patients completed the trial (Hazard ratio=0.425,95% CI 0.222-0.813, p=0.0097). Considering the mortality caused bycardiovascular events, the number of the placebo group at 52 week is14.77%, with 26 death in 176 patients, and 9.71% in the rhNRG-1 group.So from the results we can find around 40% decrease of the mortality ofrhNRG-1 administration compared with placebo group, even the placebogroup were still maintain their previous standard treatment for chronicheart failure.

We also analyzed the all-cause mortality based on the stratification ofbaseline NT-proBNP. When the NT-proBNP level is stratified into 3stratums as ≤1600 fmol/ml, ≤1600 fmol/ml and ≤4000 fmol/ml, or >4000fmol/ml, the mortality of rhNRG-1 group vs placebo group are 1.49% vs8.49%, 8.96% vs 23.33%, and 26.67% vs 28.00%, respectively. And if theNT-proBNP level is stratified as ≤4000 fmol/ml or >4000 fmol/ml, themortality of rhNRG-1 group vs placebo group are 5.22% vs 14.89%(p=0.0092), and 26.67% vs 28.00%, respectively. These results showstatistical significance that rhNRG-1 can effectively improve thesurvival of chronic heart failure patients.

Further, the patients were stratified with their baseline NYHA heartfunction class, to be class III or class IV. The all-cause mortality ofclass III patients in rhNRG-1 group or placebo group is 6.06% (8 deathin 132 patients) and 15.49% (22 death in 142 patients), respectively,p=0.0189. While the all-cause mortality of class IV patients in rhNRG-1group or placebo group is 20.93% (9 death in 43 patients) and 17.65% (6death in 34 patients), respectively, p=0.778.

What is claimed is:
 1. A method of treating chronic heart failure, themethod comprising: a) measuring a plasma level of NT-proBNP or BNP of apatient before treatment; and b) administering neuregulin-1 to thepatient when the plasma level of NT-proBNP according to the results ofstep a) is ≤4000 fmol/ml; wherein the neuregulin-1 is administered at anamount of 0.6 or 1.2 μg/kg.
 2. The method of claim 1, wherein the methodfurther comprises performing a test for the NYHA heart functionclassification of the patient, and wherein the NYHA heart functionclassification is class II or III.
 3. The method of claim 1, wherein themethod further comprises treating heart failure by further administeringone or more anti-heart failure drugs selected from a group consistingof: angiotensin-converting enzyme (ACE) inhibitors, β-blockers,Angiotensin II receptor blockers (ARBs), diuretics, and digitalis. 4.The method of claim 1, wherein the neuregulin-1 comprises an EGF-likedomain of neuregulin-1.
 5. The method of claim 1, wherein theneuregulin-1 comprises the amino acid sequence of SEQ ID NO:
 1. 6. Themethod of claim 1, wherein the administration of neuregulin-1 improvesthe clinical indication of the patient, wherein said clinical indicationis one or more of prolonged survival or reduced re-hospitalization. 7.The method of claim 1, wherein the neuregulin-1 is administered to thepatient in an introduction regimen.
 8. The method of claim 7, whereinthe introduction regimen comprises administration of neuregulin-1 for atleast 3, 5, 7 or 10 consecutive days.
 9. The method of claim 7, whereinthe neuregulin-1 is administered to the patient in a maintenance regimenafter the introduction regimen.
 10. The method of claim 9, wherein themaintenance regimen comprises administration of neuregulin-1 every 3, 5,7 or 10 days.
 11. The method of claim 1, wherein the plasma level ofNT-proBNP of the patient is ≤1600 fmol/ml.
 12. The method of claim 1,wherein the plasma level of NT-proBNP of the patient is measured byimmunoassay.